5088-46-0Relevant articles and documents
Nakazaki,M. et al.
, p. 3468 - 3473 (1977)
Nakazaki et al.
, p. 433 (1972)
An Improved Synthesis of 3,6-Dihydro- as -indacene
Dibdalli, Yuvaraja,Faúndez, Rodrigo,Preite, Marcelo,Molins, Elies,Chávez, Ivonne,Amshumali, Mungalimane K.,Morales-Verdejo, Cesar,Manriquez, Juan M.
, p. 569 - 573 (2020/09/18)
This contribution describes an updated synthetic route to 3,6-dihydro- as -indacene along with full characterization of all inter mediates. The title compound is prepared by Mannich condensation of 2-methylfuran with formaldehyde and dimethylamine hydrochloride, quaternization of the resulting amine with methyl iodide, and conversion into the ammonium hydroxide salt by treatment with silver oxide in water. Subsequent Hoffmann elimination and [6,6]-cycloaddition through pyrolysis produces a furanocyclophane, which after photooxidation, intramolecular cycloaddition, and dehydration with sodium carbonate affords 2,3,6,7-tetrahydro-1,8-dione- as -indacene. Reduction of this diketone gives a mixture of alcohols, which after dehydration under slightly basic or acidic conditions produces 3,6-dihydro- as -indacene. The structure is confirmed by X-ray diffraction, and all intermediates are characterized by means of 1H and 13C NMR spectroscopy.
NMR studies of bond order in distorted aromatic systems
Gready, Jill E.,Hambley, Trevor W.,Kakiuchi, Kiyomi,Kobiro, Kazuya,Sternhell, Sever,Tansey, Charles W.,Tobe, Yoshito
, p. 7537 - 7540 (2007/10/02)
The 4JH-C=C-Me coupling constant has been previously established1,2 as a probe of bond order. This has now been used to examine the bond orders of compounds containing severely distorted benzene nuclei. In the case of 3,4-di-tert-butyltoluene, no electronic distortions in the aromatic ring can be detected by this method. A series of moderately to severely distorted paracyclophanes show no perturbation of electronic structure, with the possible exception of 8-methyl[6]paracyclophane, which exhibits a barely significant deviation from unstrained values. These conclusions are supported by the results of SCF-MO calculations.